The broad aims of this study are to delineate areas of the brain affected during active phases of schizophrenia using regional cerebral blood flow imaging during cognitive activation. It is hypothesized that patients with schizophrenia who have active thought disorganization will fail to activate the left lateral frontal lobe of the brain and perform poorly during a task that requires the subject to access long term memory of linguistic assemblies. It is expected that this experiment will delineate differences between the disorganized and paranoid schizophrenia subtypes. Ten subjects diagnosed with schizophrenia who have active thought disorganization, ten with schizophrenia without thought disorganization but with other psychotic symptoms and ten normal controls will be recruited for comparison. Subjects will undergo Magnetic Resonance Imaging and nine Positron Emission Tomography studies using bolus infusion of Oxygen-15 labeled water during three repetitions of three cognitive states: 1) a resting state with eyes closed 2) a repeat task where the subject repeats common english nouns as they are visually presented, and ] 3) a generate task where the subject responds with a verb ( or use) for the presented noun. Several performance measures of the generate task will be obtained. Data analysis will include image averaging and subtraction procedures as well as analysis of variance to assess differences between groups and resting and activated conditions.